Reduced Precision of the Pentacam HR in Eyes with Mild to Moderate Keratoconus

Hashemi, Kattayoon; Guber, Ivo; Bergin, Ciara; Majo, F.

doi:10.1016/j.ophtha.2014.08.026

Cited by 28 publications

(22 citation statements)

References 4 publications

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“…If differences greater than our limits are seen, this is suggestive that real change has occurred. Epstein and Hashemi, respectively, reported 95% reproducibility limits for Kmax of 1.51 and 2.3 D 12 13. These are greater than our limits for early disease but less than our limits for advanced disease, and our study shows that it is essential to consider the stage of disease when assessing whether a change between scans is real or due to observer variation.…”

Section: Discussioncontrasting

confidence: 64%

“…Results from these studies suggest that repeatability and reproducibility of keratometry measurements appear to be lower in keratoconus12 13 patients than in normal eyes,14 15 but there has been inconsistency in the results in the few studies to date on interobserver and intraobserver agreement on Pentacam measures of corneal shape in keratoconus 12 13. Important clinical decisions are being made on the basis of changes in these measurements.…”

Section: Introductionmentioning

confidence: 99%

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Differential precision of corneal Pentacam HR measurements in early and advanced keratoconus

et al. 2015

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Section: Discussioncontrasting

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Differential precision of corneal Pentacam HR measurements in early and advanced keratoconus

et al. 2015

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“…), this finding could not be verified for patients with keratoconus in whom a higher variability of Kmax parameters was observed (Hashemi et al. ).…”

Section: Discussionmentioning

confidence: 90%

Analysis of pseudoprogression after corneal cross‐linking in children with progressive keratoconus

Schuerch

Tappeiner

Frueh

2016

Acta Ophthalmologica

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Our results confirm that CXL is effective in stabilizing keratoconus in children. True progression after CXL could only be verified in two of 33 eyes in a follow-up period of 37.5 months (SD ± 10 months). Two different measuring methods can help to detect diagnostic discrepancies and prevent false conclusions. Moreover, limbal vernal changes can cause transient pseudoprogression, reversible upon sufficient treatment.

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“…Similarly, Hashemi et al . 22 reported a significant improvement in inter-observer agreement for Kmax using the mean of three repeated measurements in patients with KC. We have shown a consistent improvement of LOA across all parameters and devices by a factor of approximately , as expected.…”

Section: Discussionmentioning

confidence: 90%

“…3 SD) LOA was considered as the cut-off value for the progression in keratoconic eyes. The required sample size was estimated based on a reproducibility within-subject SD of 0.83 for Kmax in patients with mild to moderate KC, which corresponds to a SD of 1.17 D (0.83/) for the difference of two measurements 22 . For the mean of 3 measurements, the SD of the difference of two means is expected to reduce to 0.68 D (1.17/).…”

Section: Methodsmentioning

confidence: 99%

Improving precision for detecting change in the shape of the cornea in patients with keratoconus

Brunner

Czanner

Vinciguerra

et al. 2018

Sci Rep

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To investigate a method for precision analysis to discriminate true corneal change from measurement imprecision in keratoconus (KC). Thirty patients with KC and 30 healthy controls were included. Coefficients of repeatability and limits of agreement (LOA) were compared using multiple measurements for inter-observer and inter-device agreement with the Pentacam HR, Orbscan IIz, and Tomey Casia SS-1000. Correlation of repeated measurements was evaluated using a linear mixed effect model (also called random effect model). A formula was derived for the theoretical expected change in precision and compared with measured change. Correlation between measurements from the same eye was small (R = 0.13). The 99.73% LOA (3 SD) of the mean of three measurements, provided better precision than 95% LOA (2 SD) of single cut-off values as expected from statistical theory for uncorrelated measurements for evidence of a significant change in corneal shape in patients with keratoconus. This enabled the determination of cut-off values for the detection of true change in corneal shape. The mean of three repeated measurements will provide better precision when there is minimal correlation. Three (rather than two) standard deviations provides a precise estimate of the LOA within or between observers and can be used as a reliable measure for identifying stage-independent corneal shape changes (progression) in keratoconus.

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Reduced Precision of the Pentacam HR in Eyes with Mild to Moderate Keratoconus

Cited by 28 publications

References 4 publications

Differential precision of corneal Pentacam HR measurements in early and advanced keratoconus

Differential precision of corneal Pentacam HR measurements in early and advanced keratoconus

Analysis of pseudoprogression after corneal cross‐linking in children with progressive keratoconus

Improving precision for detecting change in the shape of the cornea in patients with keratoconus

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